So I just read this post by the Adsense team on their blog. http://adsense.blogspot.com/2006/11/first-impressions-count.html They are saying that the first ad unit that shows up on a page is going to have the highest paying ads in it. So does that mean we should only have one ad unit; since the other ad units may just be serving low paying ads?? What do you guys think..
I've always gone for the "less is more" approach with contextual advertising, personally. it's a bit strange that they admit this though. I could've sworn in the past they said the unit that gets the most clicks will generally get the higher paying ads delivered.
There are two trains of thought on this: 1) Less ads, equals higher cost per click. or 2) More ads, more chances of clicks, with the additional clicks making up for low CPC. I've found that a middle ground works best. One or two ads per page, a half banner near the top/middle, and a bigger ad banner at the bottom.